A brushless direct current (BLDC) motor is an AC synchronous motor with permanent magnets on the rotor and windings on the stator. BLDC motors have gained popularity in recent years, including for devices such as computer hard disk drives, CD and DVD players, pumps, cooling fans and power tools.
Permanent magnets create the rotor flux and the energized stator windings create electromagnet poles, which when energized results in rotation of the rotor. Motor commutation in BLDC motors is implemented by an electronic controller and, to determine the rotor position and to know when to commutate, may implement either sensor-based control (e.g., by Hall sensors) or sensorless control (e.g., via the back EMF generated in the stator windings).